HYPOTHALAMIC-PITUITARY-ADRENAL AXIS DYSFUNCTION IN ALZHEIMERS-DISEASE- LACK OF ASSOCIATION BETWEEN LONGITUDINAL AND CROSS-SECTIONAL FINDINGS

Objective: The authors examined longitudinal hypothalamic-pituitary-ad renal (HPA) axis function in Alzheimer's disease. Method: Cortisol lev els of 30 patients with Alzheimer's disease and 17 healthy elderly sub jects were measured before and after administration of dexamethasone. These measures were repeated at 9-month intervals in the patients with Alzheimer's disease. Results: At baseline, cortisol levels were highe r in the Alzheimer's disease group before and after dexamethasone admi nistration. Although only two of the four patients whose cortisol leve ls were not suppressed by dexamethasone also had high cortisol levels before dexamethasone administration, basal and postdexamethasone corti sol levels were correlated. HPA axis dysfunction correlated with sever ity of dementia at baseline bur was not stable longitudinally and did not increase with follow-up. Conclusions: There was no association bet ween longitudinal and cross-sectional findings. The longitudinal data were not consistent with a role for the glucocorticoid cascade hypothe sis (that hippocampal cell loss in Alzheimer's disease results in hype rcortisolism, which in turn acts as a co-factor in further degeneratio n) in the pathophysiology of mild and moderate Alzheimer's disease.